VLF Data Acquisition and database storing

Transcription

1 VLF Data Acquisition and database storing VLADIMIR A. SREĆKOVIĆ Institute of Physics, P.O.Box 57, Pregrevica 118, Belgrade, Serbia Brno, April 2016

2 Outline The collaborators (Short intro. about the work of VLF Belgrade group and present our members together with all collaborators.) The ionosphere and VLF waves (Short introduction about ionosphere and VLF waves. Intro. about D region of the ionosphere and VLF waves.) The AWESOME receivers (I will present the characteristics of AWESOME receivers, and our part in it.) The AWESOME CENTRAL DATABASE (Few words about the AWESOME central database (Stanford database). Current status!.) (Atmospheric Weather Electromagnetic System for Observation Modeling and Education) Scientific applications of VLF (At the end, talk about Scientific applications of VLF and its importance. Here we have in mind detection of the stellar events: the solar flares, CME, GRB, and analysis of the ionosphere response, and modeling.)

3 This is how I see this Big Sky Earth VLF data ionosphere VLF Receivers

4 The collaborators: Belgrade VLF group: (Belgrade VLF group started working by installing the first station (AbsPAl) in 2003 at the Institute of physics. We have many members from different institutions.) - V.A. Srećković, A. Nina from Institute of Physics, Belgrade, Serbia - D. Šulić, Faculty of Ecology and Environmental Protection - D. Jevremović, and other colleagues from AOB, Vujčić, etc., and we are implementing and at the same time to testing solutions from LSST (alert sim. and etc. ). - many collaborators and colleagues all over world:, colleagues from Stanford, India, Brazil, Tunis, V. Žigman, University of Nova Gorica, Nova Gorica, Slovenia. - Take part in the activities within COST actions - members of a Stanford/AWESOME Collaboration for Global VLF Research, sponsored by NASA - We are members of the few Bilateral projects. - We are members of the projects III 44002,

5 The Ionosphere and VLF waves Schematic pres. of ionosph. layer - Characteristics of the ionosphere and their changes are very important for life and human activity on the Earth. There are numerous studies about influences of ionospheric disturbances (from outer spac.) on operation of powerful energetic systems, navigation and remote radio communication systems, the atmospheric weather, the human health and the state of the entire biosphere. - Methods of investigation of the ionospheric vertical structure are diverse and depend on the applied measuring techniques.

6 Studying the Ionosphere, techniques, D region There are few traditional techniques for studying the Ionosphere 1. What about D region Solution is We are interested in the investigations of the D region.

7 - on this slide you can see how the different waves behave as they pass through the ionosphere. - VLF 3 khz to 30 khz, wavelengths from to 0 kilometers (reflect od D) - MF 300 khz to 3 MHz - HF 3 MHz to 30 MHz (passes and reflect like this) - Microwave 300 MHz (0.3 GHz) and 300 GHz(passes) -Good thing about it is that VLF waves reflects on the D region and give us information about that ionosphere layer. -By analyzing the amplitude and phase time variations of very low frequency (VLF) radio waves emitted by many transmitters and recorded by the receivers in real time we can map that layer.

8 -On this slide you can see how the VLF waves behave at night and day. D region almost disappears at night (due to the deficiency of ionization). Later we will discuss about signal i.e. amplitude and phase behavior at night and day.

9 - Monitor (or VLF receiver) consists of a VLF antenna (small, medium or large: from few meters to several tens of meters), preamplifier box, and a line receiver box. This equipment is connected to PC and Storage media. VLF data can be recorded locally and transmit to a central database. +

10 This is a detailed scheme

11 Belgrade - talk about data from AWESOME receiver Medium large. This receiver is install 2008 at the Institute of physics and we are part of the Stanford network. We have Abspal antenna receiver too but not in the network. Daytime: monitor solar activity Nighttime: GRB, monitor atmospheric phenomena (e.g. lightning)

12 Data - There are two types of recordings made by AWESOME 1 Narrowband Several Gbyte of data in one day (1 GB 1 h) (depends low-res or hires). Take single freq. usually This type of data is called narrowband. This simply involves taking the amplitude and phase, separately, of a single narrow frequency range, specified in the software, and usually corresponding to the frequency of a VLF transmitter. Such data is generally saved in two different resolutions, hi-res (50 Hz), and low-res (1 Hz). Narrowband data takes up a much smaller amount of room, ~1GB per hour, per transmitter. Low-res can be use for some kind of observations (for phenomena that take longer )and high res are better for other. 2. Broadband Several Gbyte in one hour. Broadband saves the waveform received from antenna exactly as it was digitized, at the full 0 khz sampling rate. It thus includes information at all frequencies between the systems cutoffs (300 Hz 47 khz). Broadband data is very large, however, taking up GB per hour. spectrogram

13 - Transmitters are all over the world (~there are approx. 20 working Transm. stations ). Every transmitter transmit at fix frequency. For example Anthorn with code name GQD transmit at 19.6 khz.

14 Network AWESOME receiver all over the world. Since 2008, Belgrade station is included in the international program AWESOME (Atmospheric Weather Electromagnetic System for Observation Modeling and Education) in cooperation with Space Telecommunication and Radioscience Laboratory, Stanford University, Stanford, California 94305,

15 End of the project Last year unfortunately end of inter. project AWESOME (Atmospheric Weather Electromagnetic System for Observation Modeling and Education) No new data storing on Stanford, we can just use old data, maybe not even this in future. With Darko we are doing some thinks to solve this issue. To store in database, and a kind of online service. Than we wont to test LSST solutions (in real time analyze data before it is stored). And implement solutions from LSST alert sim.

16 Central Data Server - In Stanford: Central Data Server - We transmitted data via net in real time to central server (8 years). -Main problem was : limited flow of data through the net.

17 graphic query, - Or You can download data to use later. - Online data query on the address - Online query: Fill with needed data: transmitter stations, receiver, year, month, hour, etc. - You can see Belgrade receiver station.

18 - Snapshot of online data with amplitude and phase graphs. - Fill with needed data: transmitter stations, receiver, year, month, hour etc.

19 Snapshot of online data viewer. You can choose VLF amplitude (phase), Algire receiver station, transmitter is GQD (19.6kHz). from jan jan

20 07:00:03 07:35:31 08::59 08:46:27 09:21:56 09:57:24 :32:52 11:08:20 11:43:48 12:19:16 12:54:44 13:30:12 14:05:40 14:41:08 15:16:36 15:52:04 16:27:32 17:03:00 17:38:28 18:13:56 18:49:24 19:24:53 20:00:21 20:35:49 21:11:17 21:46:45 22:22:13 22:57:41 23:33:09 00:08:37 00:44:05 01:19:33 01:55:01 02:30:29 03:05:57 03:41:25 04:16:53 04:52:21 05:27:50 06:03:18 06:38:46 - Scientific application of VLF is that we can monotonously monitor various kind of stellar and terrestrial perturbations (detection) and analyze the ionosphere respond to it so that we can model it. Here is the example of the quiet day and below is example of active day (with lot of perturbations). We can (AWESOME) monitor a lot of various events, Solar flares (X,M,C and even B) class. GRS-s, Solar eclipse, CME Quiet Day region is formed Lymanalfa radiation (121.6 nm) 0 and ampl. change correspond to this radiation NLK 24.8 khz Active Day X-ray fluxes increase suddenly and those with wavelength appreciable below 1 nm are able to penetrate dawn -here is nighttime with higher signal, (because D-region almost disappear ), sunset and sunrise with sudden change form (because of formation and disappearance of D region), daytime with lower signal (due to the D region existence ).

21 -Strong solar flares penetrate to lower ionospheric region, cause transient changes - We study the influence of solar flares on electron concentration in the terrestrial ionospheric D-region by analyzing the amplitude and phase time variations of very low frequency (VLF) radio waves emitted by transmitters (all over the world) and recorded by the AWESOME receiver in Belgrade (Serbia) in real time. - Different magnitudes of solar flares were found to influence the VLF signal amplitude in the Earth-ionosphere waveguide in such specific ways, that their GOES (soft X-ray flux) class (C, M, X) can be classified from the response of the ionosphere (Grubor et al. 2005).

22 1. Investigations on diurnal and seasonal amplitude variations on VLF/LF radio signals 1.1 Diurnal amplitude variations 1.2 Seasonal amplitude variation 2. Typical amplitude and phase changes of VLF/LF radio signals induced by solar flares 2.1 Solar zenith angle dependence of amplitude perturbations 2.2 Distribution of amplitude perturbations during different solar activity

23 Amplitude (db -rel) Amplitude (db - rel) 00 km < D < 2000 km D < 00 km Diurnal amplitude variations April 20 NSC/45.90 khz NSC/45.90 khz 20 SR 1 SR 2 SS ICV/20.27 khz 20 ICV/20.27 khz 30 SR 3 SS 1 SR 1 SR 2 SS 2 DHO/23.40 khz 30 DHO/23.40 khz SR 1 SR 2 GQD/22. khz SS 20 GQD/22. khz April 2009 April 20 April 2011 SR SS Time (UT) Time (UT) a) Diurnal variation of amplitude on VLF signals at GQD/22. khz, DHO/23.40 khz, ICV/22.27 khz and NSC/45.90 khz monitored on the 18 th of April 20, b) The monthly averages of amplitude on VLF signals at GQD/22. khz, DHO/34.40 khz, ICV/22.27 khz and NSC/45.90 khz, for April 2009, 20 and 2011 The diurnal variation of amplitude has larger values during nighttime than in daytime condition, because of lower absorption during night. Taking into consideration the measured data shown in Figure a), it is possible to follow nighttime, sunrise, daytime, sunset and again nighttime propagation conditions. One, two or three minima amplitude labeled as SR 1 and SR 2 SR 3 and one or two SS 1 or SS 2 are observed during sunrise and sunset transition depending to the propagation path. Figure b) shows monthly averaged amplitude date against universal time. In all curves easily could be defined minima amplitude and times of their development are repeatable. How many minima amplitude and at what time they would be developed are based on specifications for each path. Occurrences of minima amplitude dependent on the interferences of various propagation modes, which change with the variations of the path parameters.

24 Amplitude (db -rel) 00 km < D < 2000 km Amplitude (db -rel) D < 00 km Seasonal amplitude variation We examined four radio signals recorded at Belgrade site to follow main propagation characteristics induced by different levels of illumination over 24 hours and over one year. For this purpose we analyzed measurements obtained in the years of low solar activity WINTER - SUMMER NSC/45.90 khz ICV/20.27 khz DHO/23.40 khz EQUINOX NSC/45.90 khz ICV/20.27 khz DHO/23.40 khz There is a gradual shift(difference) between winter and summer amplitude levels on radio signals GQD/22.kHz Januery 2009 June Time (UT) GQD/22. khz April 2009 October Time (UT) Fig b) Shapes of curves are similar to each other a) The Monthly averaged of amplitude on GQD/22. khz, DHO/23.40 khz, ICV/22.27 khz and NSC/45.90 khz radio signals for January and June 2009, b) The monthly averaged of amplitude on GQD/22. khz, DHO/34.40 khz, ICV/22.27 khz and NSC/45.90 khz radio signals, for April and October, 2009

25 Typical amplitude and phase changes of VLF/LF radio signals induced by solar flares 1E-5 1E-6 27 Amplitude (db -rel) Phase (deg) 00 km < D < 2000 km D < 00 km Ix (Wm -2 ) C3.13 C7.53 C5.14 C2.65 C3.13 C2.65 C7.53 C March E-5 06 March 2011 NSC/45.90 khz I X (Wm -2 ) 1E Time (UT) ICV/20.27 khz DHO/23.40 khz GQD/22. khz Time (UT) NSC/45.90 khz ICV/20.27 khz DHO/23.49 khz GQD/22. khz Path dependence Simultaneous variations of X-ray irradiance and propagation characteristics of GQD/22. khz, DHO/23.40 khz, ICV/29.27 KHz, and NSC/45.90 khz, radio signals a) amplitude perturbation during four successive flares on the 6 th March 2011 b) phase perturbation during four successive flares on the same day. Figure 6a gives an instructive example of four successive solar flares which induced amplitude perturbations on GQD/22. khz, DHO/23.40 khz, ICV/20.27 khz and NSC/45.90 khz radio signals observed in Belgrade. In Figure 6b there are perturbations of phase on same four radio signals versus universal time from 08:45 UT to 12:45 UT. amplitude and phase increase and size of amplitude and phase perturbations are in correlation with intensity of solar X-ray irradiance. Diff.path diff reaction but in correlat. with X ray flux

26 Amplitude perturbation (db) phase perturbation (deg) Statistics during March 2011 we examined almost thirty events of solar flares. For each flare we measured amplitude and phase perturbations on four VLF paths and showed them on Figure a and b. 8 6 GQD/22. khz DHO/23.40 khz ICV/20.27 khz NSC/45.90 khz March GQD/22. khz DHO/23.40 khz ICV/20.27 khz NSC/45.90 khz March Path dependence E-6 1E-5 I X (Wm -2 ) E-6 1E-5 Ix (Wm -2 ) a) Observed amplitude perturbations on GQD/22. khz, DHO/23.40 khz, ICV/29.27 KHz, and NSC/45.90 khz, radio signals as a function of solar X-ray irradiance b) Observed phase perturbation on same radio signals as a function of solar X-ray irradiance. The range of size in amplitude and phase perturbations varies for different paths.

27 Electron density (m -3 ) We used LWPC program for determining electron density enhancement induced by small and moderate solar flares occurred in March 2011 for four paths. Figure shows calculations of electron densities on reference height h = 74 km, for moments when intensity of X-ray irradiance reached peak. 1E11 GQD/22. khz DHO/23.40 khz ICV/20.27 khz NSC/45.90 khz March E Path dependence 1E9 1E8 1E-6 1E-5 I X (Wm -2 ) Electron density at reference height h = 74 km determined on four paths due to intensity of X-ray irradiance. Examined events occurred in March 2011

28 Electron density (m -3 ) Year Relfection height (km) Distribution of amplitude perturbations during different solar activity we will present our results of amplitude and phase perturbations on DHO/23.40 khz radio signal during different solar activity, as low, medium and high activity of current solar cycle 24 Amplitude perturbation (db) DHO/23.40 khz - Belgrade, J F M A M J J A S O N D DHO/23.40 khz - Belgrade for 0 A< 5.5 db (km -1 ) => The main aim of our work is to calculate enhancement of electron densities caused by minor, small, moderate and large classes of solar flares under different solar activity. Month 1E 1E DHO/23.40 khz - Belgrade C class Solar flares M class Solar flares 1E8 1E-6 1E-5 1E-4 I X (Wm -2 ) E-6 1E-5 1E-4 I X (Wm -2 ) Ne[m -3 ] 2.0E E E E E+ 1.5E+ 2.0E+ 2.5E+ 3.0E+ 3.5E+ 4.0E+ 4.5E+ 5.0E+ 5.3E+ 5.5E+ 6.0E+ 6.2E+ - from C1class to C6 class induced enhancement of electron density up to values ~ 9 m -3, - from C7 class to M1 class induced enhancement up to values ~ m -3, - if solar flare is classified as larger than M1 class, then enhancement of electron density is different in according to level of solar activity. The greatest enhancement of electron densities (red color) induced by moderate class solar flares mainly occurred in Electron density at reference height h =74 km as a function of X-ray flare intensity a) scatter plot, b) surface plot

29 -After analyzing all these perturbations we calculate the electron concentration (in this layer of ionosphere) before and after these changes and also to model ionization and recombination coefficients. References of our papers. - Sulic D., Sreckovic V. A., Mihajlov, A.: A study of VLF signals variations associated with the changes of ionization level in the D-region in consequence of solar conditions, Adv. Sp. Res Sulic D. & Sreckovic A.: A Comparative Study of Measured Amplitude and Phase Perturbations of VLF and LF Radio Signals Induced by Solar Flares, Ser. Astr. J Nina A,Cadez Vladimir M,Sreckovic Vladimir A,Sulic Desanka M (2012) Altitude distribution of electron concentration in ionospheric D-region in presence of time-varying solar radiation flux, NIMB, vol. 279, br., str Nina A,Cadez Vladimir M,Sulic Desanka M,Sreckovic Vladimir A,Zigman V (2012) Effective electron recombination coefficient in ionospheric D-region during the relaxation regime after solar flare from February 18, 2011, NIMB, vol. 279, br., str Grubor D.,Sulic D.,Zigman V (2008) Classification of X-ray solar flares regarding their effects on the lower ionosphere electron density profile, ANNALES GEOPHYSICAE, vol. 26, br. 7, str Zigman V,Grubor Davorka,Sulic Desanka M (2007) D-region electron density evaluated from VLF amplitude time delay during X-ray solar flares, JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSI, vol. 69, br. 7, str

30 Proud on paper in GRL which is The editors of GEOPHYSICAL RESEARCH LETTERS have selected our paper "DETECTION OF SHORT-TERM RESPONSE OF THE LOW IONOSPHERE ON GAMMA RAY BURSTS" to be featured as a Research Spotlight. One of the best accept. papers from AGU journals Research Spotlights summarize the research and findings of the best accepted articles for the broad Earth and space science community. almost was accepted in Nature

31 -VLF observations provide us with a good method to monitor high-energy transient phenomena of astrophysical importance, diagnostic tool. - Future plans: acquire and install new receiver and local data server with database with full online service, - With solutions imported and implemented from LSST and Veljko, Jovan & Darko we can do many things, analyze in real time

32 Thank you for your attention